Pistorius, Forensics, and Behavioral Evidence

Reeva Steenkamp was fatally shot at the home of Olympic sprinter and double-amputee Oscar Pistorius last week. Understandably, this incident has attracted international headlines, in part because it’s a stunning “tainted hero” narrative. Different stories have emerged, so last week’s annual gathering at the American Academy of Forensic Sciences was a great place for journalists to get some expert perspectives.

I was at the meetings, held in Washington, D.C. Among the thousands in attendance from around the world, I saw plenty of experts who could competently describe what it would take to establish what happened on that tragic Valentine’s Day. Some could discuss the physical evidence, some the lab reports, and others the behavioral evidence, which can be just as compelling in such cases.

Pistorius claimed he awakened during the early morning hours and heard what he believed was an intruder in the bathroom of his master bedroom. He grabbed his pistol and shot four times through the door of the locked toilet stall. But the “intruder” was his girlfriend. He’d shot her in the head, arm, and hip.

But was it justifed self-defense, manslaughter during a heated argument, or premeditated murder? That’s the question.

A pathologist can trace the wound trajectory to see if Pistorius rushed into the bathroom on his stumps, as he claimed, or took the time to strap on his prosthetic legs. Crime scene processors, blood spatter pattern interpreters, and ballistics experts can also compare aspects of the scene to Pistorius’ description of events.

They can locate where Pistorius stood when he fired the gun, as well as the angle and distance. The bullet entry wound can add details, particularly if the bullets passed through something hard like a door before entering the body. Blood spatter and the victim’s position when found can help to determine which bullet hit her first (although possibly not definitively).

In addition, toxicology tests can determine if Pistorius had been drinking or using any kind of substance, including steroids. Such tests will also show if Steenkamp had any substances in her system.

However, none of these processes can address vital questions about victimology. The nature of the relationship will be evaluated, which means interviews with neighbors, relatives, associates, and friends who knew them well. If these two had a history of arguing, for example, or were currently having issues over something, this must be included in the incident calculations.

Based on witness reports, prosecutors say that Pistorius intended to kill Steenkamp following a loud argument. One person described a gunshot, a woman screaming, and more shots. Still, the witnesses might have been pretty far away.

In addition, it seems likely to investigators that if Pistorius felt threatened enough to get a gun, he would have checked to see if Steenkamp was in bed. Why didn't he call out before he shot, to be sure the person behind the door was truly a potential danger to him. People who rely on guns for home defense generally know to warn an intruder that they are armed – especially if they share the home with others. Pistorius will be asked such questions.

Pistorius’ profuse weeping in court does not necessarily corroborate his story, as he could have been shedding tears of self-pity or just putting on an act to try to persuade the court that he deserved to be freed on bail (which was granted).

Another factor that plays a part is that Pistorius’s home is in a gated community. The investigatgion thus far has turned up no documentation that he feared intruders or had experienced threats on his life. His awareness of the area's safety record would be evaluated, and perhaps his degree of paranoia.

Thus, the incident remains ambiguous. State of mind, the likelihood of erroneous perception, and personal history in such situations do matter, so along with physical evidence, behavioral evidence will surely play a significant role.

I wonder whether your comment about testosterone was triggered by the leading detective wrongly assuming and announcing that testosterone was found in the bathroom after wrongly identifying vials based purely upon his prejudices and without any forensic analysis of the contents of the vials?

Anyway, of greater implication on the possible volatility of Mr Pistorius, than the possible use of testosterone, is the developmental effects of losing his legs at 11 months old and growing up being "different" and the inevitable emotionally abusive experiences of ridicule and derision he would have endured from his peers throughout his childhood. The implications this would have upon the stability of his HPA axis, and thus mood and anger regulation, are massive. Such evidence is only recently coming to light, of how developmental experience shapes our stress response, and is still shrouded in much mystery, uncertainty, suspiciousness and cross-examination. It is something that has yet to enter in to the public consciousness and be widely accepted, but if the time is put in to weigh up all the evidence that is amassing, then the influence is undeniable and it is only the finer details that we need to iron out.

Could it be that the same core thing that drove this man to greatness, was also behind a hidden volatility?

I wasn't stating anything about him in that sentence, I was stating what the tox lab would screen for, especially since we've had athletes erupt from excessive steroid use. If they didn't screen they'd be remiss.

I agree that there would be developmental issues, but in court they'd take second seat behind physical evidence that contradicts his story. If he's convicted, criminologists can then research what might have been a factor from his background. For my part, I was addressing the immediate investigation.